1. Field of the Invention
The present invention relates to a liquid chromatograph-mass spectrometer using, for example, the atmospheric pressure ionization method.
2. Description of Related Art
A specimen component which flows out from a liquid chromatograph unit arrives at an atomizer together with a traveling phase solvent via a Teflon pipe. The atomizer is heated to a temperature of 180.degree..about.330.degree. C. whereby the specimen component and the traveling phase solvent are heated and atomized. The atomized specimen component and traveling phase solvent subsequently arrive at a desolvent chamber wherein most of the traveling phase solvent is vaporized and removed and the remaining components are then introduced into an atmospheric pressure ionization chamber. In the atmospheric pressure ionization chamber, a needle electrode for causing corona discharge is provided, and via the corona discharge the solvent molecules are ionized. From the solvent ions thus produced, electric charges are transferred to the specimen molecules whereby the specimen molecules are ionized. The ionized specimen molecules thus produced are introduced into the main body of a mass spectrometer via an intermediate pressure region, and the result of mass spectrometry is outputted from a data processing device or central processing unit (CPU) in the form of a mass spectrum.
The heating temperature of the atomizer is determined depending upon the boiling temperature and the heat of vaporization of a traveling phase solvent to be used. Thereby, an optimum temperature which causes a stable atomization varies depending upon the kind of the traveling phase solvent and the mixture ratio thereof when the traveling phase solvent is composed of two or more components. Further, in the case of a gradient measurement wherein the mixture ratio of the traveling phase solvent varies depending upon time, the optimum heating temperature of the atomizer also varies depending upon time.
In the atmospheric pressure ionization method, the temperature of the atomizer greatly affects the detection sensitivity of a specimen so that a correct temperature setting is very important for obtaining a desirable spectrum of the specimen.
In the conventional liquid chromatograph mass spectrometer, the temperature of the atomizer is manually set and controlled by a person performing the measurement via an atomizer temperature controller.
Examples of the liquid chromatograph mass spectrometer using the atomospheric pressure ionization method are disclosed in JP-A-59-210358 (1984) and JP-A-63-241849 (1988).
In the conventional liquid chromatograph mass spectrometer of this kind, the temperature of the atomizer is manually set by a person performing the measurement solely depending upon his or her experience. Namely, the conventional atomizer temperature controller is constituted independently from the CPU serving as the data processing device and a manual temperature setting is performed via the atomizer temperature controller. For this reason, there is a problem that the temperature setting is difficult for beginners. Further when a gradient analysis with the liquid chromatograph mass spectrometer is required to be performed, it is necessary to vary the atomizer temperature depending upon the mixture ratio of a traveling phase solvent, but there is no provision for changing the atomizer temperature rapidly and stably.